This proposal is a five-year training plan designed to prepare the Principal Investigator for a career as an independent patient-oriented researcher with an interest in the genetic epidemiology of lung disease. Through the completion of these projects as well as the pursuit of course work in clinical and genetic epidemiology, the candidate will develop the necessary skills to design and implement family-based genetic association studies, including gene-gene and gene-environment interaction. The proposal is a collaboration between the Division of Pulmonary and Critical Care Medicine and the Departments of Public Health Genetics and Environmental Health and includes experts in cystic fibrosis, genetic epidemiology, environmental health and toxicology. The primary scientific goal of this research is to analyze the genetic determinants of lung disease variability in patients with cystic fibrosis (CF). Aim 1 will be a retrospective cohort study, using the National CF database, to quantify the effect of CF genotype on CF clinical manifestations, including lung function and mortality. Aim 2 will be a prospective study to examine for linkage and association between severe CF lung disease and a candidate gene that influences glutathione synthesis. DNA will be collected from CF patients and their biological parents. Transmission disequilibrium testing (TDT) will be performed on the trios looking for unequal segregation of glutayl-cysteine-ligase catalytic subunit (GLCLC) polymorphisms from parents to CF patients with severe lung disease. Aim 3 will examine for an association between severe CF lung disease and polymorphisms of glutathione-S-transferase M1 and TNF-alpha also using a TDT. As these polymorphisms may influence glutathione synthesis and function, gene-gene interaction with GLCLC polymorphisms will be examined using a case-only study design and logistic regression. Finally, in aim 4, through the use of validated questionnaires and methods of residence location, environmental exposure to tobacco smoke and air pollutants will be measured to test for gene-environment interaction. These projects have strong clinical and public health implications both in terms of predicting high-susceptibility patients that may develop severe lung disease as well as increasing our understanding of the mechanisms of CF lung function decline.